1. Field of the Invention
The present invention relates to a storage system and virtualization method.
2. Description of the Related Art
In order to handle large quantities of various types of data at government agencies, enterprises, and educational establishments, for example, data are managed using a relatively large-scale storage system. This storage system comprises at least one storage control apparatus. The storage control apparatus comprises a multiplicity of storage devices, for example, and is able to provide a RAID (Redundant Array of Inexpensive Disks)-based storage area. At least one or more logical devices (also known as logical volumes) are formed in a physical storage area that is provided by a storage device group. A host computer (‘host’ hereinbelow) carries out the writing of data and the reading of data by issuing write commands and read commands to the logical devices.
In order to improve the stability and so forth of data, the storage system is able to store the same data in each of a plurality of logical devices. For example, as a first conventional technology, the storage system is able to store the same data in different logical devices in the same storage control apparatus or is able to store the same data in logical devices in different storage control apparatuses (Japanese Application Laid Open No. 2007-150409).
According to this conventional technology, by storing data in a plurality of logical devices in the same enclosure or storing data in a plurality of logical devices located in different enclosures, even when a primary logical device is out of service, the work processing can be continued by using a secondary logical device. However, in order to switch from the primary logical device to the secondary logical device, it is necessary to intentionally switch the access destination device of the host from the primary logical device to the secondary logical device and the switching operation takes time.